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Arthropods, Echinoderms Phylum Arthropoda • Characteristics – Largest group of animals – Have jointed appendages which include legs, antennae, claws and pincers – Have bilateral symmetry, segmented bodies, exoskeletons, a body cavity, a digestive system with two openings and a nervous system – Most have separate sexes and reproduce sexually Arthropods • Body Segments – Bodies of these animals are divided into segments similar to segmented worms – Some have many segments, others have segments that are fused together to form body regions • Exoskeleton – A hard outer covering that supports and protects the internal body and provides places for muscle to attach. – Doesn’t grow as the animals does, it is shed and replaced during a process called molting Insects • Have three body regions • Head – Has a pair of antennae, eyes and a mouth • Thorax – Three pairs of legs and one or two pairs of wings if present are attached here • Abdomen – Where reproductive structures are found Insects • Have an open circulatory system that carries digestive food to cells and removes wastes • Insect blood doesn’t carry O2 instead air enters and exits through openings called spiracles found on the abdomen and thorax • Are the only invertebrate animals that can fly Metamorphosis • A series of changes that an insect goes through • Two types – Complete • Includes stages of egg, larva, pupa, and adult • Ex. Butterflies, bees, flies – Incomplete • Includes stages of egg, nymph, adult • The nymph form molts several times before becoming an adult • Ex. Grasshoppers, crickets Insects & Food • Feed on a number of things have different mouth parts to obtain food • Grasshoppers and ants have large mandibles for chewing • Butterflies and honey bees have siphons for lapping up nectar • Aphids and mosquitoes have mouth parts that are adapted for piercing into plants or other organisms Insects success • Insects are extremely successful based these reasons – Tough flexible, waterproof exoskeleton – Ability to fly – Rapid reproduction cycles – Small sizes • Insects have other adaptations that allow them to be successful ORDER LEPIDOPTERA What is the difference between a moth (1st picture) and a butterfly (2nd) ? Moth antennae end in clubs, they’re bodies are often furrier and when at rest, their wings are flat (butterflies rest with the wings pointing up Arachnids • Have two body regions – Cephalothorax and an abdomen • Four pairs of legs and no antennae • Many are adapted to kill prey with poison glands, stingers, or fangs • Some are parasites Arachnids • Scorpions – Have sharp, poison filled stinger at the end of abdomen. – Have a well-developed appendages which they can grab their prey. • Spiders – Can’t chew their food, release enzymes into prey to digest it—then suck the predigest liquid into its mouth. – Have book lungs where O2 and CO2 are exchanged. Brown recluse bites cause necrosis (death of tissue). Arachnids • Mites & Ticks – Most are parasites – Ticks have specialized mouthparts to remove blood from the host. – Ticks often carry disease such as Lyme disease. Centipedes & Millipedes • Have long bodies and many segments, exoskeleton, jointed legs, antennae and simple eyes. • Found in damp environments • Reproduce sexually • Make nests for eggs and stay with them until they hatch. • Centipedes are predators • Millipedes feed on decaying plant matter. Crustaceans • Have one or two pair of antennae and mandibles, which are used for crushing food. • Most live in water, but some live in moist environments on land—such as pill bug. • Have five pair of legs, first pair of legs are claws for catching and holding food. Crustaceans • Swimmerets are appendages on the abdomen which help in movement and are used in reproduction; also force water over the gills used in O2 and CO2 exchange • If a crustacean loses an appendage it can regenerate it • Include crabs, crawfish, shrimp, lobster, and sowbugs (rolypolys) Value of Arthropods • A source of food • Agriculture would be impossible without bees and other insects to pollinate crops • Useful chemicals are obtain from some arthropods • Important part of ecological community Controlling Insects • Not all arthropods are of value some are pests that carry disease or can damage crops Controlling Insects • Common ways to control insects – Insecticides, but these also kill non-harmful insects – Biological controls • Types of bacteria, fungi, and viruses can be used to control insects • Natural predators being released to kill the harmful insect • Some how interfere with reproduction of the particular insect Origin of Arthropods • Some fossils are more than 500 million years old • Scientist hypothesized that arthropods probably evolved from an ancestor of segmented worms because they have body segments • The hard exoskeleton and walking legs allowed arthropods to be among the first animals to live successfully on land Phylum Enchinodermata • Characteristics – Have an endoskeleton covered by a thin, bumpy or spiny epidermis – Radial symmetrical—allowing them to sense food, predators and other things in the environment from all directions – Have mouth, stomach, intestines – Feed on a variety of plants and animals – Have no head or brain, but have a nerve ring that surrounds the mouth – Also have cells that respond to light and touch Water-Vascular System • A characteristic unique to echinoderms • Allows them to move, exchange CO2 and O2, capture food, and release wastes • It is a network of water-filled canals with thousands of tube feet connected to it. • Tube feet—hollow, thin walled tubes that ends in a suction cup. – As pressure in the tube feet changes the animal is able to move along by pushing out and pulling in its tube feet Types of Echinoderms • Sea Stars – Echinoderms with at least 5 arms arranged around a central point – Uses tube feet to open shells of prey, once open pushes its stomach into shell and uses an enzyme to digest it – Reproduce sexually – Can repair themselves by regeneration Types of Echinoderms • Brittle Stars – Have fragile, slender, branched arms that break off easily – This adaptation allows them to survive – They can regenerate broken off body parts – Use flexible arms for movement and tube feet to get food into their mouths Types of Echinoderms • Sea Urchins & Sand Dollars – Disk or globe-shaped animals covered in spines – Spines help in movement and in burrowing – Also can protect them from predators – Sea Urchins have five tooth like structures around their mouth Types of Echinoderms • Sea Cucumber – Soft bodied echinoderms – Have a leathery covering – Have tentacles around their mouth and rows of tube feet on their upper and lower surfaces – When threatened, they may expel their internal organs which will then be regenerated in a few weeks Value of Echinoderms • Feed on dead organisms in the marine environment • Help recycle material • Used for food • Possible sources of medicine • Sea stars can help control the population of other organisms Origin of Echinoderms • Date back more than 400 million years ago • Earliest echinoderms had bilateral symmetry as adults • Scientists hypothesize that echinoderms more closely resemble animals with backbones than any other group of invertebrates – Have similar embryos that develop similar to vertebrates – Complex body systems